The nature of chromophores in high-extractives mechanical pulps: Western red cedar ( <i>Thuja plicata</i> Donn) chemithermomechanical pulp (CTMP)
Bibliographic record
Abstract
Abstract The utilization of western red cedar mechanical pulp is limited by low brightness caused by a high chromophore content. In this paper we identify these chromophores and provide a possible mechanism for their formation during the mechanical pulping process. Diffuse reflectance ultraviolet (DRUV) and Fourier-transform infrared (DRIFT) spectra were recorded for western red cedar chemimechanical pulp treated with hydrogen peroxide, sodium borohydride and acetic anhydride. Treatment with hydrogen peroxide was conducted over different time periods. The spectra indicate that three carbonyl-containing chromophores contribute to light absorption in the visible region. Two conjugated ortho -quinones contributed most of the color. These quinones were formed by oxidation and polymerization of lignans during the refining process. The third chromophore was coniferaldehyde. There was a large initial time lag for the reaction of peroxide with coniferaldehyde relative to reaction time with the quinones. We ascribe this to differences in topochemistry. It was deduced that coniferaldehyde was mainly associated with lignin in the interior of the fiber wall, whereas the quinones were derived from lignans that had been deposited on the fiber surface. Identification of the three chromophores provides a basis for studies of the kinetics of brightening of western red cedar mechanical pulps.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".